I, too, have never heard of such a thing, and I have my doubts. Reminds me of when an Irish-American radio and TV pundit claimed that his father saw "no Irish need apply" signs in the mid-twentieth century. Pure blarney.
It was very definitely a real thing:
"No Irish Need Apply" as were the "Gentiles Only" signs.Glad the U.S. has moved past that. Here is one man's memoir of growing past anti-Jewish bigotry, helped by his service in the U.S. Army:
Gentiles Only: Boyhood Memories of an Ordinary Bigotry